2. Session 1
Ratio – Introduction and Terminology
Ratio - Properties
Combining ratios
Proportion – Properties
Session 2
Variation – Properties
Comparison of fractions – Part 1
Comparison of fractions – Part 2
Problem Set – 1
Problem Set -2
www.georgeprep.com 9985-372-371
Ratio, Proportion and variation
3. Ratio, Proportion and Variation – Session 1
• Ratio – Introduction and Terminology
www.georgeprep.com 9985-372-371
4. Ratio – What is it?
Ratio: Comparison of magnitude of two quantities.
www.georgeprep.com 9985-372-371
The ratio of the expenses of A and B is 5:9. If the sum of their
expenses is Rs. 28000.
- What is A’s expense?
- By how much is B’s expense greater than A’s expense?
5. Ratio – Problems on basic understanding
www.georgeprep.com 9985-372-371
What is the value of A:B:C ? If,
a) A:B:C =
1
3
∶
1
2
∶
1
5
b)
A
3
=
B
2
=
C
5
6. Ratio – Terminology
Terminology
Antecedent and consequent
Let the ratio of A’s age and B’s age = a:b and B’s age and C’s age = b:c
Duplicate ratio of their ages =
Triplicate ratio of their ages =
Sub-duplicate ratio of their ages =
Sub-triplicate ratio of their ages =
www.georgeprep.com 9985-372-371
7. Ratio – Terminology
⁻ If 5a+2 : 12a+4 is the triplicate ratio of 3:4, what is the value of a?
www.georgeprep.com 9985-372-371
8. Ratio, Proportion and Variation – Session 1
• Ratio – Properties
www.georgeprep.com 9985-372-371
9. Ratio – Properties
Properties of Ratios
Value of ratios when multiplied or divided by the same number remains the
same
www.georgeprep.com 9985-372-371
10. Ratio – Properties
Properties of Ratios
Change of values of proper and improper fractions when the same value is added or subtracted
to the Nr and the Dr.
www.georgeprep.com 9985-372-371
Proper Fraction Improper Fraction
11. Ratio – Properties
Properties of Ratios
If
𝑎
𝑏
=
𝑐
𝑑
=
𝑒
𝑓
……. then
𝑎 + 𝑐 + 𝑒 +⋯
𝑏+𝑑+𝑓+⋯
= each of
𝑎
𝑏
,
𝑐
𝑑
… As long as (𝑏 +
𝑑 + 𝑓 + ⋯ ) ≠ 0
www.georgeprep.com 9985-372-371
12. Ratio – Properties
Properties of Ratios
• Given
𝑎
𝑏
,
𝑐
𝑑
,
𝑒
𝑓
, the value of
𝑎+𝑐+𝑒
𝑏+𝑑+𝑓
will be between the lowest and highest fraction.
www.georgeprep.com 9985-372-371
13. Ratio – Properties
Properties of Ratios - Summary
• Value of ratios when multiplied or divided by the same number remains the
same
• Change of values of proper and improper fractions when the same value is
added or subtracted to the Nr and the Dr.
• If
𝑎
𝑏
=
𝑐
𝑑
=
𝑒
𝑓
……. then
𝑎 + 𝑐 + 𝑒 +⋯
𝑏+𝑑+𝑓+⋯
= each of
𝑎
𝑏
,
𝑐
𝑑
… As long as (𝑏 + 𝑑 + 𝑓 + ⋯ ) ≠
0
• Given
𝑎
𝑏
,
𝑐
𝑑
,
𝑒
𝑓
, the value of
𝑎+𝑐+𝑒
𝑏+𝑑+𝑓
will be between the lowest and highest fraction.
www.georgeprep.com 9985-372-371
17. Ratio – Problems
www.georgeprep.com 9985-372-371
If A:B = 3:1, C:B = 2:1, C:D = 1:3 what is the value of A:D?
1) 1:2 2) 2:1 3) 1:3 4) None of these
18. Ratio – Problems
www.georgeprep.com 9985-372-371
A has thrice the amount of money that B has, B has twice
the amount of money that C has and thrice the amount of
money with C is equal to four times the amount of money
with D. The amount of money with D is what percentage of
the amount of money with A?
1) 200 2) 25 3) 12.5 4) None of these
23. Proportion – Problems
www.georgeprep.com 9985-372-371
Ratio of p:q is the same as that of q:r, where p, q and r are
positive numbers. If p = 16 and r = 100, find q.
1) 40 2) 64 3) 24 4) None of these